Corrosion prevention for heat exchanger devices and pool heaters

ABSTRACT

Disclosed herein are heat exchanger devices comprising an outer shell defining an interior chamber that is configured to pass a heat transfer fluid therethrough, a tube at least partially disposed within the interior chamber and in thermal communication with the heat transfer fluid, the tube being connected to a pool and configured to flow water from the pool therethrough such that the water flowing through the tube exchanges heat with the heat transfer fluid, and a coating disposed on an interior surface of the tube contacting the water from the pool, the coating comprising Nickel. The coating can comprise an additive, such as an electroless Nickel coating. The coating can also be selected from the group consisting of polytetrafluoroethylene (PTFE), Boron Nitride (BN), Silicon Carbide (SiC), aluminum oxide (Al2O3), carbon (C), and carbon allotropes.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to corrosion prevention. Particularly, examples of the present disclosure relate to corrosion prevention for heat exchanger devices and pool heater systems.

BACKGROUND

Pool heaters can typically employ a thermal fluid system to provide heat to swimming pools. A pool heater, in principle, can convert a fuel or energy input, such as products from a gas-fired combustion, to thermal energy in pool water by conducting a heat exchange inside of a heat exchanger. Pool heaters utilizing heat exchangers can be employed in a variety of applications, such as residential pools and/or commercial pools. Residential pool heaters, which are intended for use with residential pools, typically operate on a less-demanding schedule (e.g., fewer daily hours) and/or a smaller volume of water than commercial pool heaters. Commercial pool heaters are certified by several organizations, such as the American Society of Mechanical Engineers (ASME), and are typically designed for long daily hours (as much as a 24/7 schedule) and higher energy demands during operation, such as requiring a higher heating temperature and/or higher frequency of use. Because of these reasons, commercial and/or ASME certified pool heaters are generally required to include heat exchangers that have more durable materials, as compared to those of residential pool heaters, to handle the aggressive operating conditions.

In prior practice, residential pool heaters typically include a Copper fin-tube heat exchanger for high thermal efficiency and low overall cost. In commercial and/or ASME certified pool heaters, the heat exchanger typically includes a Copper heat exchanger having thicker tube walls (as compared to residential counterparts) or a Cupro-Nickel heat exchanger having thicker tube walls. The thicker wall can extend the life of the heat exchanger. Cupro-Nickel, being an alloy of Copper with some amount of Nickel, can enhance the corrosion resistance and durability of the heat exchanger but at the cost of roughly twice that of Copper. Accordingly, it can be cost-prohibitive to use Cupro-Nickel for many existing systems.

Therefore, there is a need for a pool heater heat exchanger that is inexpensive, durable, and/or chemically robust enough to employ in long-term operations.

SUMMARY

These problems are addressed by the disclosed technology, as are other needs that will become apparent upon reading the description below in conjunction with the drawings. The present disclosure relates generally to corrosion prevention. Particularly, examples of the present disclosure relate to corrosion prevention for heat exchanger devices and pool heater systems.

Disclosed herein is a heat exchanger device comprising an outer shell defining an interior chamber, a tube at least partially disposed within the interior chamber, and a coating disposed on an interior surface of the tube. The interior chamber can be configured to pass a heat transfer fluid therethrough. The tube can be in thermal communication with the heat transfer fluid. The tube can also be connected to a pool and configured to flow pool water from the pool therethrough. In such a manner, the water flowing through the tube can exchange heat with the heat transfer fluid.

The coating can be disposed on the interior surface of the tube which contacts the water from the pool. The coating can comprise Nickel and phosphorus. The coating can comprise phosphorus in an amount from approximately 1% to approximately 12% by weight, and Nickel in an amount from approximately 88% to approximately 99% by weight, based on the total weight of the coating. The coating can further comprise an additive. The additive is selected from the group consisting of: polytetrafluoroethylene (PTFE), Boron Nitride (BN), Silicon Carbide (SiC), aluminum oxide (Al₂O₃), carbon (C), and carbon allotropes. Alternatively, or in addition, the coating can comprise an electroless Nickel coating.

The tube can comprise Copper. When combined with the coating, the coating can confer certain properties to the tube. The coating can confer erosion resistance to the tube that is from approximately 1.7 to approximately 3.0 times greater than that of the tube without the coating, based on the American Society for Testing and Materials G73 Standard Test Method for Liquid Impingement Erosion using a Rotating Apparatus (2017). The coating can also confer corrosion resistance to the tube that is from approximately 20% to approximately 2000% more corrosion resistant than the tube without the coating, based on the American Society for Testing and Materials B368 Copper-Accelerate Acid Salt Spray Test (2014).

Also disclosed herein are pool heaters comprising a heat source and heat exchangers of the disclosed technology. The heat source can be configured to provide heat to the heat transfer fluid.

Also disclosed herein is a heat exchanger device configured to heat pool water. The heat exchanger device can comprise a first chamber defining a first volume and a second chamber defining a second volume. The first chamber can be configured to pass pool water therethrough, and the first chamber can also comprise a coating on the inner surface which contacts the pool water. The second chamber can be configured to pass a heat transfer fluid therethrough to thereby effect a heat exchange.

The coating can be selected from the group consisting of: polytetrafluoroethylene (PTFE), Boron Nitride (BN), Silicon Carbide (SiC), aluminum oxide (Al₂O₃), carbon (C), and carbon allotropes. Furthermore, the coating can comprise an electroless Nickel coating.

These and other aspects of the disclosed technology are described herein along with the accompanying figures. Other aspects, features, and elements of the disclosed technology will become apparent to those of ordinary skill in the art upon reviewing the following description of specific examples of the disclosed technology. While features of the disclosed technology may be discussed relative to certain examples and figures, the disclosed technology can include one or more of the features or elements discussed herein. Further, while one or more examples may be discussed as having certain advantageous features, one or more of such features may also be used with the various other examples of the disclosure discussed herein. In similar fashion, while certain examples, implementations, and embodiments may be discussed below with respect to a given device, system, or method, it is to be understood that such examples can be implemented in various other devices, systems, and methods of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate multiple examples of the presently disclosed subject matter and serve to explain the principles of the presently disclosed subject matter. The drawings are not intended to limit the scope of the presently disclosed subject matter in any manner.

FIG. 1 illustrates an example heat exchanger device, in accordance with the present disclosure.

FIG. 2A illustrates a schematic diagram of an example pool heater system, in accordance with the present disclosure.

FIG. 2B illustrates a schematic diagram of an example pool heater system, in accordance with the present disclosure.

FIGS. 3A-3C illustrate a perspective view, a top-down view, and a side view of an example heat exchanger device, respectively, in accordance with the present disclosure.

FIGS. 4A and 4B illustrate a perspective view and a side view of an example heat exchanger device, respectively, in accordance with the present disclosure.

FIG. 5 illustrates a rendering of a water heater for a pool, in accordance with the present disclosure.

FIG. 6 illustrates a schematic diagram of an example coating system for heat exchangers, in accordance with the present disclosure.

DETAILED DESCRIPTION

In general, the present disclosure relates to a water heater comprising a heat exchanger. The heat exchanger can comprise a series of tubes through which water passes. Additionally, the heat exchanger can be positioned to transfer heat from combustion gases originating a combustion chamber to the water passing through the series of tubes. The heat exchanger can further comprise a header. The header can include an inlet through which water can enter the heat exchanger and an outlet through which water can exit the heat exchanger.

As stated above, a problem with current heat exchanger devices for pools is that the conventional materials used therein, such as Copper and Cupro-Nickel, are prohibitively expensive, insufficiently durable, and/or insufficiently chemically robust enough to employ in long-term operations. Due to the need for commercial pool heaters to comply with ASME guidelines, pool heaters need heat exchanger devices made with a material sufficiently durable to handle the increased demand and harsh operating conditions associated with a commercial pool heater.

The disclosed technology relates to a Nickel-coated pool heater heat exchanger. The disclosed technology can improve the heat exchanger (HX) properties and reduce costs over conventional designs for the pool heater. The enhanced HX properties can include, as non-limiting examples, greater erosion resistance, greater corrosion resistance, improved scaling resistance, and greater heat transfer capability. Additionally, the disclosed technology can reduce costs by requiring a smaller overall footprint relative to traditional Copper HX, shorter HX length relative to traditional Copper HX, fewer materials relative to Cupro-Nickel HX or other alloy HX, and fewer tooling requirements as compared to conventional heat exchangers.

The disclosed technology can include an outer shell (e.g., a plurality of walls) defining an interior chamber, and the interior chamber can be configured to pass a heat transfer fluid therethrough. The disclosed technology can also include a tube disposed at least partially within the interior chamber and in thermal communication with the heat transfer fluid. The tube can be fluidly connected to a pool and can flow water from the pool through the tube. Thus, the tube can facilitate heat transfer between the heat transfer fluid and the pool water. The interior surface of the tube can include a coating, and the coating can comprise Nickel and an additive, such as in an electroless Nickel coating.

Although certain examples of the disclosure are explained in detail, it is to be understood that other examples or applications of the disclosed technology are contemplated. Accordingly, it is not intended that the disclosure is limited in its scope to the details of construction and arrangement of components set forth in the following description or illustrated in the drawings. Other examples or applications of the disclosure are capable of being practiced or carried out in various ways. Also, in describing the examples, specific terminology will be resorted to for the sake of clarity. It is intended that each term contemplates its broadest meaning as understood by those skilled in the art and includes all technical equivalents which operate in a similar manner to accomplish a similar purpose.

Herein, the use of terms such as “having,” “has,” “including,” or “includes” are open-ended and are intended to have the same meaning as terms such as “comprising” or “comprises” and not preclude the presence of other structure, material, or acts. Similarly, though the use of terms such as “can” or “may” are intended to be open-ended and to reflect that structure, material, or acts are not necessary, the failure to use such terms is not intended to reflect that structure, material, or acts are essential. To the extent that structure, material, or acts are presently considered to be essential, they are identified as such.

By “comprising” or “containing” or “including” is meant that at least the named compound, element, particle, or method step is present in the composition or article or method, but does not exclude the presence of other compounds, materials, particles, method steps, even if the other such compounds, material, particles, method steps have the same function as what is named.

Ranges described as being between a first value and a second value are inclusive of the first and second values, as well as all values therebetween. Likewise, ranges described as being from a first value and to a second value are inclusive of the first and second values, as well as all values therebetween.

It is also to be understood that the mention of one or more method steps does not preclude the presence of additional method steps or intervening method steps between those steps expressly identified.

The components described hereinafter as making up various elements of the disclosure are intended to be illustrative and not restrictive. Many suitable components that would perform the same or similar functions as the components described herein are intended to be embraced within the scope of the disclosure. Such other components not described herein can include, but are not limited to, for example, similar components that are developed after development of the presently disclosed subject matter.

Reference will now be made in detail to examples of the disclosed technology, such as those illustrated in the accompanying drawings. Wherever convenient, the same references numbers will be used throughout the drawings to refer to the same or like parts.

FIG. 1 illustrates a heat exchanger device 100 in accordance with the present disclosure. By way of illustration and not limitation, the heat exchanger device 100 in FIG. 1 is illustrated as a slab or straight shell-and-tube heat exchanger. However, it is to be understood that the heat exchanger device 100 can be any heat exchanger configured to transfer heat between two or more materials. Suitable examples of a heat exchanger can include, but are not limited to, shell and tube, plate, plate and shell, . . . , plate and fin, . . . , fluid, waste heat recovery units, . . . , microchannel, helical coil, spiral, and the like.

As shown, the heat exchanger device 100 can include a first chamber 110 (e.g., comprising one or more walls) defining a first volume and a second chamber 120 (e.g., comprising one or more walls) defining a second volume. The first volume can be fluidly separated from the second volume. The first chamber 110 can be outside (or otherwise substantially surrounding) the second chamber 120, or vice versa. The first chamber 110 and the second chamber 120 can otherwise be in contact with one another such that the first volume and the second volume can be in thermal communication with one another. For example, the second chamber 120 can be wrapped around an exterior surface of the first chamber 110. In FIG. 1, the first chamber 110 is illustrated as an outer shell, and the second chamber 120 is illustrated as a serpentine tube. Although, it is to be understood that the first chamber 110 can be the tubes and the second chamber 120 can be the outer shell.

As shown, the first chamber 110 can be configured to pass a heat transfer fluid therethrough, and the second chamber 120 can be configured to pass pool water therethrough. It is contemplated that other fluids can be passed through the second chamber 120, if desired. It is also contemplated that the fluid flow paths through the first chamber 110 and the second chamber 120 can be switched. That is to say that, the first chamber 110 can be configured to pass pool water therethrough, and the second chamber 120 can be configured to pass a heat transfer fluid therethrough.

In FIG. 1, the second chamber 120 can include a coating 130 on at least a portion of the inner surface defining the second volume. It is also understood that the coating 130 can be, alternatively or additionally, disposed on the inner surface of the first chamber 110 defining the first volume and/or the outer surface of the second chamber 120. In the illustrated example of a shell-and-tube heat exchanger discussed herein with respect to FIGS. 3A-3C, the coating 130 can be disposed on the inner surface of the second chambers 120 (i.e., the tubes). If the heat exchanger device 100 is a plate heat exchanger, the coating 130 can be disposed on the inner surface of the plates. In such a manner, the coating 130 can prevent, or substantially reduce, the corrosion and general decomposition of the materials in the second chamber 120 and the heat exchanger device 100.

For example, the first chamber 120 and/or the heat exchanger device 100 can comprise Copper. Copper can be susceptible to corrosion and erosion when in use for long periods of time under harsh conditions. The coating 130 can delay, partially, or entirely mitigate these processes. The second chamber 120 and/or the heat exchanger device 100 can, alternatively or additionally, comprise any metal. Suitable examples of a metal can include, but are not limited to, any Group 4 through 12 transition metal (such as Copper, Gold, Iron, Platinum, Titanium, Tungsten, and the like), any group 13 through 16 metalloid (such as Aluminum, Tin, and the like). The first chamber 120 and/or the heat exchanger device 100 can further comprise a metal alloy. A metal alloy can comprise a mixture of any of the example metals as described above.

The coating 130 can comprise Nickel and can aid in the corrosion resistance of whichever chamber the coating 130 is disposed on. The coating can also comprise phosphorus and/or other additives. Suitable examples of an additive can include, but are not limited to, polytetrafluoroethylene (PTFE), Boron Nitride (BN), Silicon Carbide (SiC), aluminum oxide (Al₂O₃), carbon (C), and carbon allotropes. The coating 130 can be an electroless Nickel coating, comprising Nickel and an additive.

The coating 130 can comprise phosphorus in an amount from approximately 1% to approximately 20% (e.g., from 1% to 19%, from 1% to 18%, from 1% to 17%, from 1% to 16%, from 1% to 15%, from 1% to 14%, from 1% to 13%, from 1% to 12%, from 1% to 11%, from 1% to 10%, from 2% to 10%, from 2% to 11%, from 2% to 12%, from 3% to 12%, from 4% to 12%, from 5% to 12%, from 1% to 9%, from 1% to 8%, from 1% to 7%, from 1% to 6%, or from 1% to 5%) by weight, based on the total weight of the coating 130.

The coating 130 can comprise Nickel in an amount from approximately 80% to approximately 99% (e.g., from 81% to 99%, from 82% to 99%, from 83% to 99%, from 84% to 99%, from 85% to 99%, from 86% to 99%, from 87% to 99%, from 88% to 99%, from 89% to 99%, from 90% to 99%, from 91% to 99%, from 92% to 99%, from 93% to 99%, from 94% to 99%, or from 95% to 99%) by weight, based on the total weight of the coating 130.

The coating 130 can be configured to confer certain properties to the second chamber 120 and/or any portion of the heat exchanger system 100 on which the coating 130 is disposed (such as the first chamber 110). Suitable examples of properties that the coating 130 can confer to the heat exchanger system 100 can include, but are not limited to, corrosion resistance, erosion resistance, anti-fouling, scaling resistance, bio-toxicity, fungo-toxicity, anti-rust, combinations thereof, and the like.

The coating 130 can confer erosion resistance to the second chamber 120 and/or any portion of the heat exchanger system 100 that is from approximately 1.7 to approximately 3.0 (e.g., from 1.8 to 3.0, from 1.9 to 3.0, from 2.0 to 3.0, from 2.1 to 3.0, from 2.2 to 3.0, from 2.3 to 3.0, from 2.4 to 3.0, from 2.5 to 3.0, from 2.6 to 3.0 from 2.7 to 3.0, or from 2.8 to 3.0) times greater than the erosion resistance of the same portion of the heat exchanger system 100 without the coating 130. Accordingly, the erosion resistance of any portion of the heat exchanger system can be measured by the American Society for Testing and Materials (ASTM) G73 Standard Test Method for Liquid Impingement Erosion using a Rotating Apparatus (2017).

The coating 130 can confer corrosion resistance to the second chamber 120 and/or any portion of the heat exchanger system 100 that is from approximately 20% to approximately 2000% (e.g., from 30% to 2000%, from 40% to 2000%, from 50% to 2000%, from 60% to 2000%, from 70% to 2000%, from 80% to 2000%, from 90% to 2000%, from 100% to 2000%, from 110% to 2000%, from 120% to 2000%, from 130% to 2000%, from 140% to 2000%, from 150% to 2000%, from 160% to 2000%, from 170% to 2000%, from 180% to 2000%, from 190% to 2000%, from 200% to 2000%, from 300% to 2000%, from 400% to 2000%, from 500% to 2000%, from 600% to 2000%, from 700% to 2000%, from 800% to 2000%, from 900% to 2000%, from 1000% to 2000%, from 20% to 1000%, from 20% to 900%, from 20% to 800%, from 20% to 700%, from 20% to 600%, from 20% to 500%, from 20% to 400%, from 20% to 300%, from 20% to 200%, from 20% to 190%, from 20% to 180%, from 20% to 170%, from 20% to 160%, from 20% to 150%, from 20% to 140%, from 20% to 130%, from 20% to 120%, from 20% to 110%, or from 20% to 100%) more corrosion resistant than the same portion of the heat exchanger system 100 without the coating 130. Accordingly, the corrosion resistance of any portion of the heat exchanger system can be measured by the American Society for Testing and Materials (ASTM) B368 Copper-Accelerate Acid Salt Spray Test (2014).

FIG. 2A illustrates a pool heater 200. As shown, the pool heater 200 can comprise a heat source 210 and a heat exchanger (e.g., the heat exchanger device 100). The heat source can include, for instance, a gas-fired combustion chamber or an electric water heater (e.g., an electric resistance pool heater). While the pool heater 200 is shown and described as including the heat exchanger device 100 as described above, it is understood that other forms of heat exchangers can be used. As shown, the pool heater 200 can comprise one or more pumps 220. The pool heater 200 can be configured to move water via the pumps 220 to recirculate water from the pool 230. The pool heater 200 can also include other components such as valves, heat exchangers, diverters, coolers, and the like.

FIG. 2B illustrates another water heating system for a pool. The water heating system can comprise a pump 220 that can draw water from a pool and direct the water along an inlet pipe 216 and through a filter 210 to a heater 200. The heater 200 can include, for instance, a gas-fired combustion chamber. The arrows in the water heating system show the general direction of flow of the water. After the water is heated in the heater 200 it can be returned to the pool via outlet pipe 218. As shown, the block 206 is illustrated to encapsulate other components that may be present along the inlet pipe 216, such as one or more chemical probes, sensors, transducers, chillers, filters (in addition to filter 210), and the like.

FIGS. 3A-3C illustrate a perspective view, a top-down view, and a side view of an example of the heat exchanger device 100, respectively. As shown, the heat exchanger device 100 can be in the form of a slab shell-and-tube heat exchanger. The outer shell (e.g., the first chamber 110) can define an interior volume (e.g., the first volume) that is configured to pass a heat transfer fluid therethrough. The heat transfer fluid can be for heating the pool water (e.g., combustion gases) or for chilling the pool water (e.g., a refrigerant). The tubes (e.g., the second chamber 120) can be at least partially disposed within the interior volume such that the tubes are in thermal communication with the interior volume (and therefore the heat transfer fluid). The tubes can be connected to various other components such as pipes, valves, pumps, and the like connected to a pool. Water from the pool can be configured to flow through the tubes such that the water can exchange heat with the heat transfer fluid. As would be appreciated, increasing the number and/or the length of the tubes can increase the available surface area for the heat transfer, and therefore improve the efficiency of the heat exchanger.

The coating 130 can be coated on the interior of the tubes (e.g., the second chamber 120) because the tubes can be configured to pass the pool water therethrough. As such, the coating 130 can reduce and/or prevent the pool water from corroding and/or eroding the tubes. It is understood that the coating 130 can also modify additional properties of the tubes to improve the service life and/or efficiency of the tubes.

FIGS. 4A-B illustrate a perspective view and a side view of another example of the heat exchanger device 100, respectively. As shown, the heat exchanger device 100 can be in the form of a helical coil shell-and-tube heat exchanger. The outer shell (e.g., the first chamber 110) can define an interior volume (e.g., the first volume) that is configured to pass a heat transfer fluid therethrough. The heat transfer fluid can be for heating the pool water (e.g., combustion gases) or for chilling the pool water (e.g., a refrigerant). The tubes (e.g., the second chamber 120) can be at least partially disposed within the interior volume such that the tubes are in thermal communication with the interior volume (and therefore the heat transfer fluid). The tubes can be connected to various other components such as pipes, valves, pumps, and the like connected to a pool. Water from the pool can be configured to flow through the tubes such that the water can exchange heat with the heat transfer fluid. As would be appreciated, increasing the number of coils and/or the length of the tubes can increase the available surface area for the heat transfer, and therefore improve the efficiency of the heat exchanger.

The coating 130 can be coated on the interior of the tubes (e.g., the second chamber 120) because the tubes can be configured to pass the pool water therethrough. As such, the coating 130 can reduce and/or prevent the pool water from corroding and/or eroding the tubes. It is understood that the coating 130 can also modify additional properties of the tubes to improve the service life and/or efficiency of the tubes.

As described above, the disclosed technology comprising the coating 130 can provide enhanced desirable heat transfer characteristics when compared to traditional systems using Copper, Cupro-Nickel, and/or Nickel-plating.

Furthermore, while the second chamber 120 is described above as being a single chamber, the disclosed technology includes a heat exchanger having a plurality of second chambers 120.

FIG. 5 illustrates an example water heater 500 for a pool comprising the heat exchangers and devices of the present disclosure. The water heater 500 can comprise a combustion chamber 504, a heat exchanger 506, and an exhaust vent 510. The heat exchanger 506 can be any of the heat exchangers and/or heat exchanger devices or systems as described herein. The water heater 500 can be an “up fired” water heater in that the combustion chamber 504 can be located below the heat exchanger 506. However, it should be understood that the examples described herein can also be applied to “down fired” water heaters as well as water heaters having other configurations. Furthermore, the examples described herein can also be applied to water heating devices that use heat sources other than combustion, such as electric or solar heat sources.

When in operation, the water heater 500 can receive fuel, such as natural gas or propane, via the fuel line 502. The fuel can be combined with air and ignited at one or more burners in the combustion chamber 504. The ignition of the fuel and air in the combustion chamber can produce hot combustion gases that flow upward and around the outside surfaces of the heat exchanger tubes of the heat exchanger 506. Heat from the combustion gases can be transferred through the walls of the heat exchanger tubes to heat water passing through the interior of the heat exchanger tubes. As described above, the interior of the heat exchanger tubes can also comprise a coating on at least a portion of the surfaces which contact the water.

The heat exchanger 506 and the heat exchanger tubes can have any one of a variety of shapes and configurations to optimize the transfer of heat from the combustion gases passing over the outer surface of the heat exchanger 506 to the water passing through the interior of the heat exchanger tubes. After passing through the heat exchanger 506, the combustion gases can exit the water heater via the exhaust vent 510.

In addition to the heat exchanger tubes, the heat exchanger 506 can comprise a header 508. As shown in FIG. 5, the header 508 can attach to the open side of the heat exchanger 506. The header 508 can comprise an inlet and an outlet that permit the flow of water into and out of the heat exchanger 506. However, it should be understood that the illustrated water heater 500 described herein can apply to headers having other configurations.

The foregoing is a simplified description of the operation of a water heater to provide a framework for the illustrations described herein. It should be understood that various other components can be included in the water heater, but a description of those components is not included so as not to obscure the examples described herein.

Also disclosed herein are systems for coating a heat exchanger, such as the heat exchanger device 100. FIG. 6 illustrates an example coating system 600 for coating the interior surface of a heat exchanger in accordance the present disclosure. The coating system 600 can include a tank 605 of a coating solution, which can comprise a nickel-based solution. The tank 605 can be coupled to a pump and valve assembly 610 and a source line 607 which can feed the coating solution to a heat exchanger 618. The valve portion of the pump and valve assembly 610 can permit other lines to attach to the source line 607. For instance, a pre-treatment line 622 and a water line 624 may be coupled to the source line 607 via a valve portion of the pump and valve assembly 610. The operation of the pump and valve assembly 610 can be controlled by a controller, such as pump controller 630.

At an end opposite the tank 605, the source line 607 can be coupled to a heat exchanger inlet of the heat exchanger 618. A heat exchanger outlet of the heat exchanger 618 can be coupled to a return line 608 which can return the coating solution to the tank 605. In the coating system 600 shown, the heat exchanger 618 can be mounted on an optional rack holder. The coating system 600 also shows an optional air compressor 616 attached to the source line 607.

During operation of the coating system 600, the pump 610 can pump a fluid through the source line 607 to the heat exchanger 618. The pump controller 630 can control the pump and valve assembly 610 to supply water via the water line 624 and the source line 607 to rinse the interior of the heat exchanger to ensure it is clean before applying the coating solution. As another option, the pump controller 630 can control the pump and valve assembly 610 to supply a pre-treatment solution to the interior of the heat exchanger via the pre-treatment line 622 and the source line 607. The pre-treatment solution can be a solution that facilitates bonding between the interior surface of the heat exchanger 618 and the coating solution that will follow the pre-treatment solution through the heat exchanger 618. The return line 608 can include a quick connection point 614 for attaching additional lines for draining the water or pre-treatment solution so that the water or pre-treatment solution is not mixed with the coating solution in tank 605.

As a next step in the process, the pump and valve assembly 610 can pump the coating solution from tank 605 through the source line 607 to the heat exchanger inlet. Once inside the heat exchanger 618, the coating solution can be designed to react with the interior surface of the heat exchanger and form a protective coating thereon. The coating solution may be held within the heat exchanger 618 for a predefined period of time to permit the protective coating to form on the interior surface of the heat exchanger 618. For instance, the combination of the pump 610 and a valve (not shown) in the return line 608 can be used to hold the coating solution within the heat exchanger 618 for a period of time. Maintaining the coating solution under pressure within the heat exchanger for a period of time can facilitate creating a uniform protective coating throughout the interior surface of the heat exchanger 618.

After the coating solution has had sufficient time to form a protective coating on the interior surface of the heat exchanger 618, the controller can open the valve (if present) in the return line 608 and the remaining coating solution, that has not attached to the interior surface as the protective coating, can be returned to the tank 605 via the return line 608. After application of the coating solution, as an optional step, a rinse of water or another solution can be pumped through the heat exchanger 618 to wash out any remaining coating solution that has not attached to the interior surface of the heat exchanger 618. As another optional step, the controller can activate the air compressor 616 to force air through the heat exchanger 618 to remove any remaining water or other material. The air compressor 616 can be attached to the source line 607 at the quick connection point 612. The air compressor 616 can also be in communication with and controlled by the air controller 631. Once the coating process is completed, the heat exchanger 618 with its protective interior coating is ready for installation in a water heating appliance.

Also disclosed herein are methods of coating a heat exchanger, such as the heat exchanger device 100. The methods described above, while described by being implemented by the coating system 600 on the heat exchanger device, can also be implemented by any other suitable coating systems, general purpose computers, and the like, on to other suitable heat exchangers.

Certain examples, embodiments, and implementations of the disclosed technology are described above with reference to block and flow diagrams of systems and methods according to examples or implementations of certain aspects of the disclosed technology. It will be understood that one or more blocks of the block diagrams and flow diagrams, and combinations of blocks in the block diagrams and flow diagrams, respectively, can be implemented by computer-executable program instructions. Likewise, some blocks of the block diagrams and flow diagrams may not necessarily need to be performed in the order presented, may be repeated, or may not necessarily need to be performed at all, according to some examples or implementations of the disclosed technology. That is, the disclosed technology includes the performance of some, or all steps of the methods and processes described herein in conjunction with the performance of additional steps not expressly discussed herein. Further, the present disclosure contemplates methods and processes in which some, but not all, steps described herein are performed.

While the present disclosure has been described in connection with a plurality of exemplary aspects, as illustrated in the various figures and discussed above, it is understood that other similar aspects can be used, or modifications and additions can be made to the described aspects for performing the same function of the present disclosure without deviating therefrom. For example, in various aspects of the disclosure, methods and compositions were described according to aspects of the presently disclosed subject matter. However, other equivalent methods or composition to these described aspects are also contemplated by the teachings herein. Therefore, the present disclosure should not be limited to any single aspect, but rather construed in breadth and scope in accordance with the appended claims.

EXAMPLE

The following exemplary use cases describe examples of a typical implementation of the disclosed subject matter. They are intended solely for explanatory purposes and not limitation.

A pool heater 200 can utilize a heat exchanger 100 for heating and/or recirculating the pool water. The heat exchanger 100 can be in the form of a slab shell-and-tube heat exchanger having an outer shell 110 and one or more tubes 120. The interior volume defined by the outer shell 110 can be configured to pass a heat transfer fluid therethrough. As a more specific example, the outer shell 110 can be connected to a combustion furnace that produces hot combustion gases, which are then passed to the outer shell 110. The one or more tubes 120 can be at least partially contained within the outer shell such that the hot combustion gases in the outer shell 110 can thermally communicate with the tubes 120. In such a manner, heat can be transferred from the combustion gases to the tubes 120 and further transferred to any material, such as pool water, within the tubes 120.

The one or more tubes 120 and/or the entire heat exchanger 100 can be made from Copper or a Copper alloy. When pool water from the pool flows through the tubes 120, the Copper tubes 120 can be susceptible to corrosion and/or erosion, thus reducing the lifetime of the heat exchanger 100. A coating 130 can be disposed (coated) on the interior surface of the tubes to counteract the harsh and harmful effects of the pool water. The coating 130 can comprise Nickel in the form of an electroless Nickel coating. Such a heat exchanger 100 can be approximately 1.7 times to approximately 2.0 times more erosion resistant than the same heat exchanger comprising a Cupro-Nickel alloy material and approximately 2.7 times to approximately 3.0 times more erosion resistant than the same heat exchanger comprising uncoated Copper, according to the ASTM G73 Standard Test Method for Liquid Impingement Erosion using a Rotating Apparatus (2017). 

What is claimed is:
 1. A heat exchanger device comprising: an outer shell defining an interior chamber that is configured to pass a heat transfer fluid therethrough; a tube at least partially disposed within the interior chamber and in thermal communication with the heat transfer fluid, the tube being connected to a pool and configured to flow water from the pool therethrough such that the water flowing through the tube exchanges heat with the heat transfer fluid; and a coating disposed on an interior surface of the tube contacting the water from the pool, the coating comprising Nickel.
 2. The heat exchanger device of claim 1, wherein the coating further comprises phosphorus.
 3. The heat exchanger device of claim 2, wherein the coating comprises phosphorus in an amount from approximately 1% to approximately 20% by weight, based on the total weight of the coating.
 4. The heat exchanger device of claim 1, wherein the coating comprises Nickel in an amount from approximately 80% to approximately 99% by weight, based on the total weight of the coating.
 5. The heat exchanger device of claim 1, wherein the coating comprises an additive.
 6. The heat exchanger device of claim 5, wherein the additive is selected from the group consisting of: polytetrafluoroethylene (PTFE), Boron Nitride (BN), Silicon Carbide (SiC), aluminum oxide (Al₂O₃), carbon (C), and carbon allotropes.
 7. The heat exchanger device of claim 1, wherein the coating comprises an electroless Nickel coating.
 8. The heat exchanger device of claim 1, wherein the tube comprises Copper.
 9. The heat exchanger device of claim 1, wherein the coating confers erosion resistance to the tube that is from approximately 1.7 to approximately 3.0 times greater than the erosion resistance of the tube without the coating, in accordance with the American Society for Testing and Materials G73 Standard Test Method for Liquid Impingement Erosion using a Rotating Apparatus (2017).
 10. The heat exchanger device of claim 1, wherein the coating confers corrosion resistance to the tube that is from approximately 20% to approximately 2000% more corrosion resistant than the tube without the coating, in accordance with the American Society for Testing and Materials B368 Copper-Accelerate Acid Salt Spray Test (2014).
 11. A pool heater comprising: a heat source configured to provide heat to a heat transfer fluid; and a heat exchanger in fluid communication with the heat source, the heat exchanger comprising: an outer shell defining an interior chamber that is configured to pass the heat transfer fluid therethrough from the heat source; a tube at least partially disposed within the interior chamber and in thermal communication with the heat transfer fluid, the tube being connected to a pool and configured to flow water from the pool therethrough such that the water flowing through the tube exchanges heat with the heat transfer fluid; and a coating disposed on an interior surface of the tube contacting the water from the pool, the coating comprising Nickel.
 12. The pool heater of claim 11, wherein the coating comprises an additive.
 13. The pool heater of claim 12, wherein the additive is selected from the group consisting of: polytetrafluoroethylene (PTFE), Boron Nitride (BN), Silicon Carbide (SiC), aluminum oxide (Al₂O₃), carbon (C), and carbon allotropes.
 14. The pool heater of claim 11, wherein the coating comprises an electroless Nickel coating.
 15. The pool heater of claim 11, wherein the tube comprises Copper.
 16. The pool heater of claim 11, wherein the coating confers erosion resistance to the tube that is from approximately 1.7 to approximately 3.0 times greater than the erosion resistance of the tube without the coating, in accordance with the American Society for Testing and Materials G73 Standard Test Method for Liquid Impingement Erosion using Rotating Apparatus (2017).
 17. The pool heater of claim 11, wherein the coating confers corrosion resistance to the tube that is from approximately 20% to approximately 2000% more corrosion resistant than the tube without the coating, in accordance with the American Society for Testing and Materials B368 Copper-Accelerate Acid Salt Spray Test (2014).
 18. A heat exchanger device configured to heat pool water, the heat exchanger device comprising: a first chamber defining a first volume that is configured to pass the pool water therethrough, the first chamber having an inner surface comprising a coating; and a second chamber defining a second volume that is configured to pass a heat transfer fluid therethrough to thereby effect a heat exchange between the heat transfer fluid and the pool water.
 19. The heat exchanger device of claim 18, wherein the coating is selected from the group consisting of: polytetrafluoroethylene (PTFE), Boron Nitride (BN), Silicon Carbide (SiC), aluminum oxide (Al₂O₃), carbon (C), and carbon allotropes.
 20. The heat exchanger device of claim 18, wherein the coating comprises an electroless Nickel coating. 